GM Service Manual Online
For 1990-2009 cars only

Object Number: 1340812  Size: LF
Master Electrical Component List
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

Circuit Description

The transmission range (TR) switch is part of the park/neutral position and back-up lamp switch assembly and is mounted on the transmission manual shaft. The TR switch is a multi-signal switch. The transmission control module (TCM) monitors voltage on the four TR switch signal circuits, A, B, C, and P. Each gear selector lever position supplies voltage to one or more of the signal circuits in a unique pattern. In order to determine the gear range selected by the driver, the TCM compares the voltage combination on the signal circuits to a TR switch combination table stored in memory.

Diagnostic Aids

Refer to Transmission Range Switch Logic for valid combinations of switch signal circuits A, B, C and P.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. By disconnecting the TR switch, the voltage path for all TR switch circuits would be removed and the TCM should recognize all circuits as open. The scan tool should display LOW for all range signals.

  2. This step tests the TR switch wiring for an open or lack of ground from the TCM.

  3. This step tests the TR switch wiring and the TCM by providing a voltage path through a fused jumper wire. When jumpered, the scan tool range signal A should change to HI.

  4. This step tests the TR switch wiring and the TCM by providing a voltage path through a fused jumper wire. When jumpered, the scan tool range signal B should change to HI.

  5. This step tests the TR switch wiring and the TCM by providing a voltage path through a fused jumper wire. When jumpered, the scan tool range signal C should change to HI.

Step

Action

Values

Yes

No

1

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Select TR Sw. on the scan tool.
  4. With the scan tool, observe the TR Sw. display while selecting each transmission range: P, R, N, D, I and L.

Does each selected transmission range match the scan tool TR Sw. display?

--

Go to Intermittent Conditions in Engine Controls - 2.2 L (L61)

Go to Step 2

2

  1. Inspect the park/neutral position (PNP) switch assembly for the following:
  2. • Damage
    • Loose or missing mounting hardware
    • Proper adjustment
  3. Inspect the shift cable for the following:
  4. • Damaged or stretched cable
    • Proper adjustment

Did you find and correct a condition?

--

Go to Step 15

Go to Step 3

3

With the scan tool, observe the TR Sw. A/B/C/P display.

Does the scan tool TR Sw. A/B/C/P parameter indicate LOW for all range signal states?

--

Go to Step 12

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the TR switch 10-way connector.
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool TR Sw. A/B/C/P parameter indicate LOW for all range signal states?

--

Go to Step 5

Go to Step 9

5

  1. Using the digital multimeter (DMM) and the J-35616 connector test adapter kit, measure the voltage from Signal A of the TR switch 10-way connector to B+.
  2. Measure the voltage from Signal B of the TR switch 10-way connector to B+.
  3. Measure the voltage from Signal C of the TR switch 10-way connector to B+.
  4. Measure the voltage from Signal P of the TR switch 10-way connector to B+.

Does the voltage measure within the specified value at all four terminals?

10-12 V

Go to Step 6

Go to Step 10

6

Connect a fused jumper wire from the TR switch 10-way connector, signal A circuit, to B+ while monitoring the scan tool TR Sw. A/B/C/P parameter.

When the signal A circuit is jumpered, do any other signal circuits indicate HI?

--

Go to Step 11

Go to Step 7

7

Connect a fused jumper wire from the TR switch 10-way connector, signal B circuit, to B+ while monitoring the scan tool TR Sw. A/B/C/P parameter.

When the signal B circuit is jumpered, do any other signal circuits indicate HI?

--

Go to Step 11

Go to Step 8

8

Connect a fused jumper wire from the TR switch 10-way connector, signal C circuit, to B+ while monitoring the scan tool TR Sw. A/B/C/P parameter.

When the signal C circuit is jumpered, do any other signal circuits indicate HI?

--

Go to Step 11

Go to Step 13

9

Test the signal circuit or circuits of the TR switch that did not indicate LOW for a short to voltage.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

10

Test the signal circuit or circuits of the TR switch that did not indicate proper voltage for an open.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

11

Test the affected signal circuits of the TR switch for a shorted together condition.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

12

Test the voltage supply circuit of the TR switch for an open or short to ground.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

13

Replace the TR switch. The TR switch is part of the park/neutral position switch.

Refer to Park/Neutral Position Switch Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the TCM.

Refer to Transmission Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Turn ON the ignition, with the engine OFF.
  2. With the scan tool, observe the TR Sw. display while selecting each transmission range: P, R, N, D, I and L.

Does each selected transmission range match the scan tool TR Sw. display?

--

System OK

Go to Step 2